As a technological example for controlling a phase component of a signal and performing signal processing, a technology of noise suppression which is focused on a phase spectrum is disclosed in patent document 1 and non-patent document 1. The technologies described in patent document 1 and non-patent document 1 suppress an amplitude spectrum related to a noise and randomly shifts the phase spectrum by a value smaller then or equal to π/4 simultaneously. The technologies described in patent document 1 and non-patent document 1 realize a suppression of the noise which cannot be suppressed only by attenuation of the noise spectrum by shifting the phase spectrum at random.